Although many people assume that commonly used substances such as caffeine and ephedrine can alter the effects of alcohol, few studies have systematically examined these possibilities. This study examines whether caffeine or ephedrine may influence the effects of alcohol on how people feel (e.g., drunk, sleepy) and perform (e.g., in reaction time tasks). Young adults come to the lab for 4 different sessions. During these sessions, they drink alcohol or placebo, and they swallow 2 capsules that contain caffeine, ephedrine or placebo. They stay in the lab the whole day and regularly answer questions about how they are feeling, and what effects the alcohol has on them. They also perform tasks (e.g., reaction time tasks), and their blood pressure and heart rate is measured throughout the day. After the session is over, they are escorted to the GCRC for an overnight stay. They answer questions and perform tasks at certian timepoints during the evening and the next morning. Analysis of the data will allow us to determine whether caffeine or ephedrine can alter how alcohol makes people feel or perform, or the effects alcohol has on physiological variables such as blood pressure and heart rate.